IDENTIFICATION AND CHARACTERIZATION OF THE DYSTROPHIN ANCHORING SITE ON BETA-DYSTROGLYCAN

Dystrophin, the product of the Duchenne muscular dystrophy gene, is tightly associated with the sarcolemmal membrane to a large glycoprotein complex. One function of the dystrophin-glycoprotein complex is to Link the cytoskeleton to the extracellular matrix in skeletal muscle. However, the molecular interactions of dystrophin with the membrane components of the dystrophin-glycoprotein complex are still elusive, Here, we demonstrate and characterize a specific interaction between beta-dystroglycan and dystrophin. We show that skeletal muscle and brain dystrophin as well as brain dystrophin isoforms specifically bind to beta-dystroglycan, To localize and characterize the dystrophin and beta-dystroglycan interaction domains, we reconstituted the interaction in vitro using dystrophin fusion proteins and in vitro translated beta-dystroglycan. We demonstrated that the 15 C-terminal amino acids of beta-dystroglycan constituted a unique binding site for the second half of the hinge 4 and the cysteine-rich domain of dystrophin (amino acids 3054-3271), This dystrophin binding site is located in a proline-rich environment of beta-dystroglycan within amino acids 880-895, The identification of the interaction sites in dystrophin and beta-dystroglycan provides further insight into the structure and the molecular organization of the dystrophin glycoprotein complex at the sarcolemma membrane and will be helpful for studying the pathogenesis of Duchenne muscular dystrophy.